<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        body, html {
            height: 100%;
        }

        .outter {
            border: 5px solid black;
            position: relative;
        }
        .inner {
            border: 5px solid red;
            height: 50%;
            position: absolute;
        }
    </style>
</head>
<body>

    <div class="outter">
        <div class="inner">程序员小山与Bug</div>
        <br/><br/><br/><br/><br/><br/><br/><br/><br/><br/>
    </div>


</body>
</html>